Prostaglandins have been shown to stimulate bone resorption and to be elevated in gingiva from patients with periodontal disease. Model systems have been developed and will be further perfected to study the effect of anti-inflammatory agents on the control of prostaglandin formation or action. Bovine gingiva is used as a model for studying drugs which inhibit prostaglandin synthesis and phospholipase action. Fetal rat bone grown in organ culture is used to test agents which inhibit prostaglandin stimulated resorption. Cultures of Pseudomonas aeruginosa which produce prostaglandin-like substances from arachidonic acid will be studied from the standpoint of a potential disease-producing organism which acts through prostaglandin mechanisms.